A THz wave falls in the electromagnetic spectrum range of around 0.1-10 THz. It has unique applications, because inter alia, its spectrum range resides in many molecular fingerprint regions. Potential applications include astronomy, wireless communications, security and safety, spectroscopy and biomedical technologies. Recent advances in THz technology have made many of these potential applications feasible. Some examples include THz imaging, spectroscopy and sensing. There are generally two types of THz wave: a pulsed T-ray and a continuous wave (CW) THz. The CW THz technology has the advantages of high spectral resolution, fast response time, tunability and low cost. However, the technology also suffers the drawbacks of low emission power, typically in the range of <10−6 Watts preventing the technology being used for certain applications.
Present photoconductive antenna (PCA) THz photomixers usually employ an interdigitated electrode design for their active region to create photocarriers which act as current source for the planar THz antenna. The interdigitated configuration generates nano-antenna oscillation in a direction perpendicular to the dipole antenna thereby reducing the overall device efficiency. The relatively large gap between finger electrodes is also not conducive to enhancing the electric field for both the pumping light and the THz wave, while resulting in relatively large circuit capacitance that is undesirable for high frequency operation.
The above-mentioned drawbacks impede the performance and/or advancements of PCA THz photomixing emitters. In view of the forgoing, it is highly desirable to develop ways which enhance the emission power of PCA THz photomixing emitters.